Polar vortex freezes US Midwest with snow and cold air

A blast of Arctic air from the polar vortex brought dangerous, bone-chilling cold to a wide swath of the United States on Tuesday, stretching from the Dakotas through Maine, with snow expected as far south as Alabama and Georgia. The Midwest was the hardest-hit region, as temperatures plunged minus 18 degrees Celsius.

A snow-covered street is seen in Saint Paul, US. (Mark J. Westpfahl/via REUTERS)

A smashed car is seen on a road in Saint Paul, US. (Mark J. Westpfahl/via REUTERS)

A snow plough clears a road in Denver. (Denver International Airport/via REUTERS)

Cars move along a snow-covered road in Denver. (Denver International Airport/via REUTERS)

Cars move along a snow-covered road in Denver. (Denver International Airport/via REUTERS)

The city skyline is seen from the North Avenue Beach at Lake Michigan. (REUTERS/Pinar Istek)

A pedestrian stops to take a photo by Chicago River. (REUTERS/Pinar Istek TPX IMAGES OF THE DAY)

The fog begins to cover the city skyline in Chicago. (REUTERS/Pinar Istek)

Students huddle in subzero temperature windchill while walking to class at the University of Minnesota in Minneapolis. (REUTERS/Eric Miller)

Jim Cleary takes a photo of the Chicago skyline from the North Avenue Beach at Lake Michigan. (REUTERS/Pinar Istek)

Pedestrians cross the street at rush hour, as bitter cold phenomenon called the polar vortex has descended on much of the central and eastern United States. (REUTERS/Pinar Istek)

A man walks along the Chicago River. (REUTERS/Pinar Istek)

A pedestrian walks by Chicago River. (REUTERS/Pinar Istek)

The James J. Versluis, a 90-foot icebreaker tugboat, breaks ice through Lake Michigan in Chicago. (REUTERS/Pinar Istek)